Film-processing method and film-processing apparatus

ABSTRACT

A film-processing method according to the present invention includes: a processing step of irradiating electron beams onto a film on a surface of an object to be processed to conduct a process to the film; an electric-current measuring step of capturing the electron beams in a vicinity of the object to be processed to measure an electric-current value during the processing step; and a detecting step of detecting an end point of the process to the film, based on an amount of electron obtained by means of a time integration of the electric-current value. According to the present invention, a suitable irradiation of the electron beams onto the film on a surface of the object to be processed can be realized. Thus, a suitable film quality can be obtained.

FIELD OF THE INVENTION

The present invention relates to a film-processing method and afilm-processing apparatus. More particularly, it pertains to afilm-processing method and a film-processing apparatus which are capableof optimally processing a film such as an insulation film between layerson a surface of an object to be processed, e.g., a wafer.

BACKGROUND OF THE INVENTION

In accordance with greater integration and increased speed ofsemiconductor devices, wiring patterns have been miniaturized, and thereduction of parasitic capacitance generated by an insulation filmbetween wirings has become increasingly important. In order to reduceparasitic capacitance generated by an insulation film between wirings ofa minute wiring pattern, various organic materials of low dielectricconstant have been developed in recent years. These organic materialshave been used to form an insulation film between layers and aprotective film as a Low-k material. This Low-k film material is knownto form an SOD film by applying the same to a surface of an object to beprocessed by means of a spin coater and baking furnace. However, many ofthe SOD films are made of an organic material, and some of the SOD filmsare inferior in mechanical strength. This is because a high porosity isemployed to obtain a low dielectric constant. Thus, an electron beamprocessing apparatus has been used to try to modify qualities of the SODfilm, such as enhancing mechanical strength, while maintaining a lowdielectric constant thereof.

An electron beam processing apparatus irradiates electron beams from aplurality of electron beam tubes onto a surface of an object to beprocessed such as a wafer to modify and cure a film such as an SOD filmon the surface of the object to be processed. Such modification andcuring is referred to as an “EB cure” below. The EB cure is carried outby setting processing conditions (process time, for example) of theelectron beam processing apparatus, with reference to back datapreviously obtained by evaluating a film of the same kind.

In modifying a film quality by using a conventional electron beamprocessing apparatus, even when processing conditions such as a processtime of the electron beam processing apparatus are set based on aprevious evaluation, it is difficult to achieve the most suitableprocess time because of an ununiform amount of irradiation of electronbeams onto an object to be processed. That is, even with the sameprocess time, the amount of electron irradiated onto an object to beprocessed may be either too much or too little. Thus, it is difficultfor a film on a surface of the object to be processed to obtain adesired film quality, which results in a reduction of throughput. Forexample, if a process time for the EB cure is insufficient, curing isnot completed and a desired film strength cannot be achieved. Thus, asuitable film quality cannot be obtained. On the other hand, an excessprocessing time for the EB cure degrades the k value, and thus asuitable film quality cannot be obtained.

SUMMARY OF THE INVENTION

The present invention is made to solve the above disadvantages. It is anobject of the present invention to provide a film-processing method anda film-processing apparatus wherein electron beams are suitablyirradiated onto an object to be processed to obtain a suitable filmquality.

The present invention is a film-processing method comprising: aprocessing step of irradiating electron beams onto a film on a surfaceof an object to be processed to conduct a process to the film; anelectric-current measuring step of capturing the electron beams in avicinity of the object to be processed to measure an electric-currentvalue during the processing step; and a detecting step of detecting anend point of the process to the film, based on an amount of electronobtained by means of a time integration of the electric-current value.

According to the present invention, by detecting an end point of theprocess to the film based on an amount of electron during the process, asuitable irradiation of the electron beams onto the film on a surface ofthe object to be processed can be realized. Thus, a suitable filmquality can be obtained.

An amount of irradiation of the electron beams onto the film ispreferably controlled by a grid electrode during the processing step.

The method according to the present invention preferably furthercomprises a calculating step of previously calculating an amount ofelectron captured before an end point of a process to a reference filmon an object to be processed, as a reference amount of electron; whereinthe detecting process detects the end point of the process to the film,based on the reference amount of electron.

The detecting step preferably detects the end point of the process tothe film, based on a temperature of a holding member which holds theobject to be processed, or a temperature of the object to be processed.

The present invention is a film-processing apparatus comprising: aprocessing unit which irradiates electron beams onto a film on a surfaceof an object to be processed to conduct a process to the film; anelectric-current sensor which captures the electron beams as anelectric-current in a vicinity of the object to be processed; anelectric-current measuring unit which measures an electric-current valueof the electric-current captured by the electric-current sensor; acalculating unit which calculates an amount of electron by means of atime integration of the electric-current value; and a detecting unitwhich detects an end point of the process to the film, based on theamount of electron.

According to the present invention, by detecting an end point of theprocess to the film based on an amount of electron during the process, asuitable irradiation of the electron beams onto the film on a surface ofthe object to be processed can be realized. Thus, a suitable filmquality can be obtained.

The film-processing apparatus preferably further comprises a gridelectrode which controls an amount of irradiation of the electron beamsonto the film.

The apparatus according to the present invention preferably furthercomprises: a storing unit which stores a reference amount of electroncaptured before an end point of a process to a reference film on anobject to be processed; wherein the detecting unit is adapted to detectthe end point of the process to the film, based on the reference amountof electron.

The detecting unit is preferably adapted to detect the end point of theprocess to the film, based on a temperature of a holding member whichholds the object to be processed, or a temperature of the object to beprocessed.

The film-processing apparatus preferably further comprises: a processingcontainer; a stage disposed in the processing container; and a pluralityof electron beam tubes which irradiate electron beams onto an object tobe processed mounted on the stage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically showing an embodiment ofa film-processing apparatus according to the present invention;

FIG. 2 is a plan view showing an example of an arrangement of electronbeam tubes of the film-processing apparatus shown in FIG. 1;

FIGS. 3A to 3C are explanatory views illustrating a principal ofdetecting an end point of a film process by using the film-processingapparatus shown in FIG. 1;

FIG. 4 is a graph showing a relationship of a voltage of a gridelectrode and a sensor current flowing through an electric-currentsensor shown in FIG. 1;

FIGS. 5A and 5B are graphs each showing a relationship of the voltageand a differential value of the sensor current shown in FIG. 4;

FIG. 6 is a graph showing a relationship of a process time, the sensorcurrent, and a temperature of a stage, for illustrating a principal ofdetecting an end point;

FIG. 7 is a view showing an example of the corresponding relationship ofan amount of electric charge incident on a wafer, a shrinking ratio, anda process time;

FIG. 8 is a cross-sectional view schematically showing anotherembodiment of a film-processing apparatus according to the presentinvention;

FIG. 9 is a graph illustrating a principal of detecting an end point byusing the film-processing apparatus shown in FIG. 8;

FIG. 10 is a cross-sectional view schematically showing anotherembodiment of a film-processing apparatus according to the presentinvention;

FIG. 11 is a cross-sectional view schematically showing anotherembodiment of a film-processing apparatus according to the presentinvention;

FIG. 12 is a cross-sectional view schematically showing anotherembodiment of a film-processing apparatus according to the presentinvention;

FIG. 13 is a graph illustrating a principal of detecting an end point byusing the film-processing apparatus shown in FIG. 12;

FIG. 14 is a graph illustrating the principal of detecting an end pointby using the film-processing apparatus shown in FIG. 12;

FIG. 15A is a view schematically showing an elevating mechanism of awafer W used in an improved film-processing apparatus; and

FIG. 15B is a view schematically showing an elevating mechanism of awafer W used in a conventional film-processing apparatus.

BEST MODE FOR EMBODYING THE INVENTION

The present invention is described below with reference to embodimentsthereof shown in the accompanied drawings.

Referring FIG. 1, an embodiment of the film-processing apparatusaccording to the present invention is described.

As shown in FIGS. 1 and 2, a film-processing apparatus 1 of theembodiment, for example, includes a decompressible processing container2 made of aluminum or the like; a stage 3 on which an object to beprocessed (wafer) W is mounted, the stage 3 being disposed on a centerof a bottom surface of the processing container 2; a plurality of (e.g.,19) electron beam tubes 4 which are concentrically arranged on an uppersurface of the processing container 2 opposed to the stage 3; and a gridelectrode 5 which controls an amount of irradiation of electron beams Bfrom the electron beam tubes 4. Under a control by a controller 6, theelectron beams B are irradiated from the respective electron beam tubes4 onto the whole surface of the wafer W mounted on the stage 3 so as tomodify qualities of a coated insulation film (referred to as “SOD film”hereinafter) formed on the surface of the wafer W. The SOD film isformed of an organic material including elements such as Si, O, C, and Has ingredients. The film formed on the surface of the wafer W is notlimited to the SOD film. The film may be other one used as an insulationfilm between layers or a protective film. A modification of qualities ofthe film by means of the electron beams is hereinbelow referred to as“EB cure” as needed.

An elevating mechanism 7 is connected to a lower surface of the stage 3.The stage 3 is vertically moved by means of a ball screw 7A of theelevating mechanism 7. The lower surface of the stage 3 and the bottomsurface of the processing container 2 are connected to each other by anextensible bellows 8 made of stainless steel. Thus, an inside of theprocessing container 2 is air-tightly held. A port 2A through which thewafer W is loaded and unloaded is formed on a peripheral surface of theprocessing container 2. A gate valve 9 is attached to the port 2A, whichcan open and close the port 2A. A gas supply port 2B is formed on a partabove the port 2A of the processing container 2. A gas exhaust port 2Cis formed on the bottom surface of the processing container 2. A gassupply source (not shown) is connected to the gas supply port 2B througha gas supply pipe 10. A vacuum exhaust system (not shown) is connectedto the gas exhaust port 2C through a gas exhaust pipe 11. In FIG. 1, thereference number 12 indicates a bellows cover.

The stage 3 has a heater (not shown). The wafer W is heated by theheater to a desired temperature. As shown in FIG. 2, the nineteenelectron beam tubes 4 are constituted by, for example, one electron beamtube 4 positioned at a center of the upper surface of the processingcontainer 2, six electron beam tubes 4 surrounding the central electronbeam tube 4, and twelve electron beam tubes 4 surrounding the sixelectron beam tubes 4. Each electron beam tube 4 has a window disposedin the processing container 2, the window transmitting an electron beam.The transmitting window is encapsulated by a transparent quartz glass.The grid electrode 5 is opposingly disposed below the transmittingwindow.

As shown in FIG. 1, the film-processing apparatus (electron beamprocessing apparatus) 1 includes an end point detecting unit 20. The endpoint detecting unit 20 detects an end point of an EB cure of the SODfilm on the surface of the wafer W. The end point detecting unit 20 has:an electric-current sensor 21 which is disposed on the upper surface ofthe stage 3 to surround the wafer W, the electric-current sensor 21capturing the electron beams from the electron beam tubes 4 in avicinity of the wafer W; an electric-current measuring unit (e.g.,ammeter) 22 which is connected to the electric-current sensor 21; anelectron amount calculating unit 23 which integrates a value measured bythe ammeter 22 by time so as to calculate an amount of electron capturedby the electric-current sensor 21; and a storing unit 26 which storesthe calculated amount of electron. The electric-current sensor 21 isformed of such material that can capture the electron beams from theelectron beam tubes 4. For example, a conductor such as metal and/or asemiconductor such as Si may be used for the electric-current sensor 21.The end point detecting unit 20 further has a temperature sensor 24which measures a temperature of the stage 3, and a time integration unit25 which integrates a value measured by the temperature sensor 24 bytime. Thus, the end point detecting unit 20 can indirectly calculate atotal amount of heat absorbed by the wafer W.

FIGS. 3A to 5 are explanatory views illustrating a principal ofmeasurement by the end point detecting device 20. As shown in FIG. 3A,an amount of irradiation of the electron beams B from the electron beamtubes 4 (see, FIG. 1) is controlled by the grid electrode 5. After theirradiation amount is controlled, the electron beams B are captured bythe electric-current sensor 21. The ammeter 22 measures the sensorcurrent from the electric-current sensor 21. Based on theelectric-current value, an amount of electron incident on theelectric-current sensor 21 from the electron beam tubes 4 can bequantitatively measured. Thus, although indirectly, an amount ofelectron incident on the wafer W positioned inside the electric-currentsensor 21 can be quantitatively measured.

It is considered that electron irradiated from the electron beam tubes 4does not have a constant energy value shown by the solid line A in FIG.3B, but has an energy distribution of a certain width shown by thedotted line B in FIG. 3B, by a voltage applied to the electron beamtubes 4. Thus, when a voltage of the grid electrode 5 is increased, asshown in FIG. 3C, the electron beams are blocked by the grid electrode 5at a predetermined grid voltage Vg. That is, the electron beams do notreach the electric-current sensor 21, and then the electric-currentvalue becomes zero. At this time, it is not considered that theelectric-current value becomes abruptly zero from a certainelectric-current value as shown by the solid line C in FIG. 3C. However,as shown by the dotted line D in FIG. 3C, it is considered that theelectric-current value gradually decreases to zero, according to adistribution of the number of electron shown by the dotted line B inFIG. 3B.

Actually, a relationship of the grid voltages and the sensor currentswas measured. FIG. 4 shows the result. It was found that the resultsshown in FIG. 4 correspond to the graph of FIG. 3C. Among the resultsshown in FIG. 4, FIG. 5A shows a graph illustrating a change ratio(dI/dV) of the sensor current with respect to the grid voltage, when thevoltage applied to the electron beam tubes 4 is 20 kV. Among the resultsshown in FIG. 4, FIG. 5B shows a graph illustrating a change ratio(dI/dV) of the sensor current with respect to the grid voltage, when thevoltage applied to the electron beam tubes 4 is 22 kV. As apparent fromFIGS. 5A and 5B, it was found that these graphs correspond to the energydistribution of electron shown in FIG. 3B. That is, the electric-currentsensor 21 can surely capture the electron beams in a favorablyreproductive manner, and thus can surely detect an amount of irradiationof the electron beams B. Therefore, the electric-current sensor 21 canbe suitably used for detecting an end point of a film process.

In this way, when the electron beams are irradiated onto the SOD film onthe wafer W, an amount of electron captured by the electric-currentsensor 21 can be grasped as an electric-current value by means of theammeter 22. As shown by the solid line A in FIG. 6, for example, theelectric-current value rapidly increases and becomes stable at a certainvalue, under the control of the grid electrode 5. Then, an EB cure ofthe SOD film on the wafer W is carried out. An amount of incidentelectron by this time can be calculated by means of a time integrationof the electric-current value. Under any given condition, there is acertain correlation of an amount of electron incident on theelectric-current sensor 21 and an amount of electron incident on the SODfilm on the wafer W. Thus, in this embodiment, an EB cure of a referenceSOD film on a wafer W is previously conducted. When optimal modifiedqualities are obtained, the electron amount calculating unit 23integrates an electric-current value detected by the electric-currentsensor 21 by time. The integrated value functions as a reference amountof electron. The reference amount of electron is stored in the storingunit 26 of the controller 6. The reference amount of electron issequentially compared with each amount of electron calculated by meansof the electron amount calculating unit 23 when the actual wafer isprocessed, so that an end point of the EB cure of the SOD film on theactual wafer W is detected. The reference amount of electron depends ona film quality of, e.g., the SOD film on the wafer W. Thus, thereference amount of electron is calculated for each kind of films.

The EB cure is carried out by a combined action of the incident electronand heat. Thus, in order to detect the optimal end point of the EB cure,a time integration of temperature can be used. Then, an EB cure of areference SOD film on a wafer W is previously carried out. Similarly tothe case wherein the reference amount of electron is calculated, whenthe optimal modified qualities are obtained, the time integration unit25 integrates a temperature detected by the temperature sensor 24 bytime. The integrated value functions as a reference amount of heat(reference integrated temperature). The reference amount of heat isstored in the storing unit 26 of the controller 6. The reference amountof heat is sequentially compared with each amount of heat calculated bymeans of the time integration unit 25 when the actual wafer isprocessed. Then, it is possible to detect an end point of the EB cure ofthe SOD film on the actual wafer W as a timing at which an end point isdetected not only based on the reference amount of electron but alsobased on the reference amount of heat. Alternatively, an end point maybe determined by comparing a value obtained by multiplying thecalculated amount of electron by the calculated amount of heat when theactual wafer W is processed, with a value obtained by multiplying thereference amount of electron by the reference amount of heat. That is,in this embodiment, in addition to quantitatively detecting an end pointof the EB cure based on the reference amount of electron, the referenceamount of heat is also used to detect the end point of the EB cure moreaccurately.

In addition, the end point may be detected by using indications such asan amount of electric-charge incident on the wafer [μc/cm²] and ashrinking ratio. The amount of electric-charge incident on the wafer iscalculated as follows: an amount of electric-current detected by theelectric-current sensor 21 is multiplied by the ratio of anelectric-current sensor area with respect to a wafer area to obtain atotal amount of electric-current incident on the wafer [μc] (calculatedvalue). Then, the calculated value is divided by the wafer area toobtain the amount of electric-charge incident on the wafer. Theshrinking ratio is a shrinking ratio of film thickness. FIG. 7 shows anexample of corresponding relationship between these indications andprocess times. In the example shown in FIG. 7, as the process timeelapses, the shrinking ratio increases and the measured/calculatedamount of electric-charge incident on the wafer also increases. Theshrinking ratio corresponds to a curing effect by means of the electronbeams. Thus, based on a previously grasped correlation between theamount of electric-charge incident on the wafer and the shrinking ratio,a film process may be terminated when an amount of electric-chargeincident on the wafer corresponding to a predetermined shrinking ratiois detected by monitoring the amount of electric-charge incident on thewafer during the film process.

When an EB cure is carried out to a film such as an SOD film, carboningredient is generally decreased at an area nearer to a surface of thefilm. Thus, a uniformity of film quality is degraded. If a film such asan SOD film is subjected to an etching or ashing process, conditions ofthe etching or ashing process are different according to depth of thefilm, so that a shape of the film after the etching or ashing processmay be deteriorated, or the etching rate may be lowered. Further, thefilm may be etched by a cleaning liquid or the like. Thus, when an SODfilm is applied on a wafer W, the applying step is divided into aplurality of steps. In the respective steps, application materials arestep by step applied onto the wafer in ascending order of carbonconcentration. Thus, an inclination of carbon concentration is providedin a direction of depth of the SOD film. As a result, the carbonconcentration is higher in the higher layer. Since the inclination ofcarbon concentration is provided in the depth direction, even if thecarbon concentration in a surface layer of the SOD film is lowered bythe EB cure, the carbon concentration in the depth direction of the SODfilm becomes substantially uniform upon termination of the EB cure,because the carbon concentration in the surface layer is made previouslyhigher. Accordingly, the above disadvantages can be eliminated.

Next, a method of detecting an end point of a film process conducted bythe electron beam processing apparatus 1 of this embodiment is describedbelow. When an EB cure of an SOD film on a wafer W is carried out, thewafer W is transferred to the electron beam processing apparatus 1 bymeans of a wafer transfer arm (not shown). Then, the gate valve 9 isopened, and the wafer W is transferred by the wafer transfer arm throughthe port 2A into the processing container 2, and is delivered onto thestage 3 waiting in the processing container 2. Thereafter, the wafertransfer arm is withdrawn from the processing container 2, and the gatevalve 9 is closed in order to air-tightly seal the processing container2. During this step, the stage 3 is elevated up by the elevatingmechanism 7, so that a gap between the wafer W and the electron beamtubes 4 is maintained at a predetermined distance.

After that, air in the processing container 2 is evacuated by the vacuumexhaust system, and an inert gas such as Ar or N₂ is supplied into theprocessing container 2 from the gas supply source. In this way, the airin the processing container 2 is replaced with the inert gas. Inaddition, a pressure of the inert gas in the processing container 2 isheld at a predetermined one. At this time, the heater of the stage 3 isactuated to heat the wafer W to hold the same at a predeterminedtemperature. Under this condition, a predetermined voltage is applied toall the electron beam tubes 4. Thus, as shown in FIG. 3B, electron beamsB of a certain energy distribution are irradiated from the respectiveelectron beam tubes 4 onto the wafer W. Then, the EB cure of the SODfilm is initiated, while an amount of irradiation of the electron beamsis controlled by the grid electrode 5.

Electrons passing through the grid electrode 5 are incident on the SODfilm on the wafer W or on the electric-current sensor 21. The ammeter 22measures the electrons captured by the electric-current sensor 21 as anelectric-current value. The measured value is outputted to thecontroller 6. In the controller 6, after the value measured by theammeter 22 is A/D converted, the electron amount calculating unit 23integrates the electric-current value by time to calculate an amount ofelectron. At the same time, the temperature sensor 24 measures atemperature of the stage 3. Similarly to calculating an amount ofelectron, the time integration unit 25 integrates a measured temperatureby time to calculate an integrated temperature (an amount of heat).

The controller 6 sequentially compares the amount of electron calculatedby the electron amount calculating unit 23 with the reference amount ofelectron. When the calculated amount of electron reaches the referenceamount of electron, the controller 6 judges that the EB cure reaches anend point. Then, a control signal is outputted to stop the irradiationof the electron beams B so as to terminate the EB cure. Alternatively,if the integrated temperature (the amount of heat) calculated by thetime integration unit 25 does not reach the reference integratedtemperature (the reference amount of heat), the EB cure may be continueduntil the integrated temperature reaches the reference integratedtemperature.

As described above, according to this embodiment, the electron beams Bare captured by the electric-current sensor 21 in a vicinity of thewafer W, an amount of electron captured by the electric-current sensor21 is measured by the ammeter 22 as an electric-current value, theelectron amount calculating unit 23 integrates the measured value bytime to obtain an amount of electron, and an end point of the EB cure isdetected based on the amount of electron. Thus, the electron beams aresuitably irradiated onto a film such as an SOD film on the wafer W, sothat the optimal EB cure may be constantly carried out. That is, asuitable film quality having a desired k value can be obtained.

In addition, according to this embodiment, a reference amount ofelectron captured by an end point of an EB cure of a reference film on awafer W is previously calculated, and an end point of an EB cure isdetected based on the reference amount of electron. Thus, an end pointof an EB cure for achieving a suitable film quality can be surelydetected, and the EB cure can be automatically terminated in real time.At that time, a temperature of the stage 3 is measured to detect an endpoint based on an integrated temperature of the measured value. Thus,the end point of the EB cure can be more accurately detected. Aprovision of the grid electrode 5 allows an amount of irradiation of theelectron beams B to be more securely controlled.

Next, other methods of detecting an end point and apparatuses for thesame are described with reference to FIGS. 8 to 12, wherein the sameparts have the same reference numbers, and characteristic featuresthereof are mainly described. FIGS. 8 and 9 show an apparatus fordetecting an end point of an EB cure by quantitatively analyzing acertain gas by using a gas analyzing unit such as a Fourier transforminfrared spectroscopic analyzing (FT-IR) unit or a mass analyzing unit.

An electron beam processing apparatus 1 shown in FIG. 8 includes aprocessing container 2, a stage 3, electron beam tubes 4, and a gridelectrode 5. The parts other than an end point detecting unit areconstituted in substantially the same manner as the above embodiment. Avacuum exhaust system 13 is connected to the processing container 2through a gas exhaust pipe 11. A gas inlet pipe 11A and a gas outletpipe 11B are connected to the gas exhaust pipe 11. An end pointdetecting unit 40 is connected to the gas exhaust pipe 11 through thepipes 11A and 11B. The end point detecting unit is, for example,composed of a mass analyzing unit, an FT-IR unit, and so on. In thisembodiment, a mass analyzing unit 40 is used.

When a gas is detached from an SOD film on a wafer W by an EB cure, thedetached gas is discharged from the processing container 2 to the gasexhaust pipe 11. The discharged gas is introduced from the gas inletpipe 11A into the mass analyzing unit 40 to analyze gas ingredientsthereof. The analyzed gas is led out from the gas outlet pipe 11B to thegas exhaust pipe 11. For example, when an EB cure is carried out to anSOD film on a surface of a wafer W, an energy of electron incident onthe SOD film causes a chemical reaction such as a polycondensationreaction. Then, water, hydrogen gas, and so on are detached from the SODfilm. The mass analyzing unit 40 sequentially determines respectivequantities of the gas ingredients of the detached gas. That is, the gasingredients of the detached gas are monitored while the EB cure iscarried out. Therefore, an end point of the EB cure can be detected,i.e., the same effect as the above embodiment can be expected.

FIG. 9 is a graph illustrating a relationship between process times ofan EB cure and concentration (intensity) of respective gas ingredients,wherein a sample wafer coated with an SOD film and a silicon waferwithout an SOD film are sequentially subjected to the EB cure. Thereference character (i) indicates an intensity of hydrogen gas. Asapparent from FIG. 9, the intensity of hydrogen gas (amount of hydrogengas) detached from the SOD film decreases as the time elapses. Thus, theintensity of hydrogen gas may be used as an indication for detecting anend point. An intensity of hydrogen gas before a suitable EB cure to theSOD film is completed is previously integrated by time, and theintegrated value is used as a reference value for judging an end point.When an EB cure of an actual wafer is carried out, an integrated valueof intensity during the EB cure and the reference value are comparedwith each other, which is similar to the above cases. A timing at whichthe integrated value of intensity reaches the reference value is judgedas an end point of the EB cure. Accordingly, the same effect as theabove embodiment can also be expected. The result shown in FIG. 9 wasobtained when the EB cure was carried out under the followingconditions.

[Conditions of EB Cure]

Temperature of Wafer: 350° C.

Inert Gas: Ar (10 Torr, 3 L/min)

Electron Beam Tube

-   -   Applied Voltage: 13 kV    -   Tube Current: 170 μA

Process Time: 5 minutes

When the mass analyzing unit 40 is used, an end point of the EB cure canbe detected as described above. However, by analyzing the detached gas,gas ingredients, which may be deposited on an inner surface of theprocessing container 2, can be otherwise grasped, for example. Bydetermining respective quantities of the gas ingredients, thickness of afilm deposited on the inner surface can be estimated. Based on thethickness, a timing suitable for cleaning the interior of the processingcontainer 2 can be estimated. In addition, by analyzing oxygen gas, itis possible to monitor whether any gas leaks from the processingcontainer 2 or not.

An irradiation of electron beams onto an SOD film causes apolycondensation reaction, and then water molecules are detached fromthe SOD film. As shown in FIG. 10, an FT-IR unit is used to determinequantity of the water molecules. The determined value is integrated bytime, and thus an end point of the EB cure can be detected similarly tothe above embodiments. In FIG. 10, the FT-IR unit 50 is connected to theprocessing container 2 through a pipe 51. Water molecules (vapor)floating above the wafer W are taken out from the pipe 51, and the FT-IRunit 50 measures an intensity of infrared absorption by hydrogen-oxygenbonding in the water molecules. By means of a time integration of theabsorption intensity, an end point of the EB cure can be detected.Naturally in this case, a gas analyzing unit such as a mass analyzingunit can be used as an end point detecting unit.

Further, by using an emission spectroscopy analysis as well, an endpoint of an EB cure can be detected. As shown in FIG. 11, a collimator61, for example, is attached on an upper part of the peripheral surfaceof the processing container 2. A spectrograph 60 is connected to thecollimator 61 through an optical fiber 62. An emission spectrum taken bythe collimator 61 and the optical fiber 62 is generated by thespectrograph 60 so as to measure an intensity of the emission spectrumwith respect to a certain wavelength of a plasma corresponding to acertain detached gas (e.g., hydrogen radical). Then, the emissionintensity is integrated by time. Based on the integrated value, an endpoint of the EB cure is detected. Also in this case, an integrated valueas a reference value is previously calculated by using a referencewafer. By comparing an integrated value obtained while an actual waferis subjected to an EB cure and the reference value with each other, anend point of the EB cure can be detected. Thus, the same effect as theabove respective embodiments can be expected.

Alternatively, an end point of an EB cure can be detected by utilizing arefractive index of an SOD film on a surface of a wafer W. During the EBcure of the SOD film on the wafer W, activation energy is imparted toorganic compounds forming the SOD film by electron incident on the SODfilm from the electron beam tubes. Then, a polycondensation reaction orthe like occurs to generate a gas. As a result, the SOD film is shrunkand cured. A refractive index of the SOD film is changed according tothe shrinking of the SOD film. Thus, an end point of the EB cure can bedetected based on a relationship between the refractive index and theshrinking ratio of the SOD film. Also in this case, the same effect asthe above respective embodiments can be expected.

In the electron beam processing apparatus 1 shown in FIG. 12, arefractive index measuring unit (e.g., a spectral ellipsometer using asingle wavelength) 70, for example, is attached on an upper surface ofthe processing container 2. The refractive index measuring unit 70measures a refractive index of the SOD film. Other parts are constitutedin substantially the same manner as those of the respective aboveelectron beam processing apparatuses 1. FIG. 13 shows a relationshipbetween process times of the EB cure, shrinking ratios of the SOD film,and refractive indices (RI) of the same, wherein the EB cure was carriedout by the electron beam processing apparatus 1 under the conditionsdescribed below. A single wavelength of 633 nm was used to measure therefractive indices. As shown in FIG. 13, both the shrinking ratio andthe refractive index increase substantially in proportion with a lapseof the process time. In detecting an end point of the EB cure, arefractive index before a suitable EB cure to a reference wafer iscompleted is previously integrated by time, and the integrated value isused as a reference value for judging an end point. When an actual waferW is subjected to an EB cure, a refractive index is integrated by time,and a timing at which the integrated value reaches the reference valueis judged as an end point of the EB cure. Also in this case, the sameeffect as the above respective embodiments can be expected.

[Conditions of EB Cure]

Pressure in Processing Container: 10 Torr

Temperature of Wafer: 350° C.

Argon Gas: 3 L/min under normal state

Electron Beam Tube

-   -   Applied Voltage: 13 kV    -   Tube Current: 260 μA

As described above, the EB cure is affected by a temperature of thewafer. Thus, an influence given to the SOD film by the temperatureduring the EB cure was investigated, while keeping the process timeconstant but changing the tube current of the electron beam tubes 4. Itwas found that, the higher the tube current is and the higher thetemperature is, the higher the shrinking ratio and hardness (elasticmodulus) become. When keeping the tube current constant but changing theprocess time, substantially the same result was obtained.

FIG. 14 shows a correlation of shrinking ratios and elastic moduli.Herein, a correlation of shrinking ratios and elastic moduli of the SODfilm is shown in which the EB cures are carried out with varioustemperatures of the wafer. As apparent from FIG. 14, the higher atemperature of the wafer is, the sharper a gradient of the elasticmodulus with respect to the shrinking ratio becomes. In addition, it wasfound that, in the same shrinking ratio, when a temperature of the waferis different, the elastic modulus is also different. In this way, arelationship between the shrinking ratio and the elastic modulus dependson a temperature of the wafer. Thus, when detecting an end point of theEB cure based on a refractive index of the SOD film so as to obtain arequired elastic modulus of the SOD film, the end point of the EB curecan be detected more accurately if an integrated temperature of atemperature of the wafer is taken into consideration. Also in this case,the same effect as the above respective embodiments can be expected.

In place of the refractive index measuring unit 70, an opticalinterference thickness meter can be attached to the processing apparatusto detect a change of film thickness. An end point of an EB cure can bedetected by using the optical interference thickness meter. During theEB cure to the SOD film, the SOD film is shrunk so that the filmthickness thereof is gradually decreased as the time elapses. Bydetecting the change of the film thickness by means of the opticalinterference thickness meter, an end point of the EB cure is detected.Similarly to the above embodiment, the end point can be detected moreaccurately if an integrated temperature of a temperature of the wafer istaken into consideration.

Although not shown, a weight detecting unit may be disposed on the stageso that a weight of the wafer may be detected by the same. In this case,a weight of a reference wafer when a suitable EB cure to the referencewafer is completed is previously stored in the storing unit as areference weight. When an actual wafer is subjected to an EB cure, aweight of the wafer is sequentially detected. A timing at which a weightof the wafer reaches the reference weight is judged as an end point ofthe EB cure.

FIGS. 15A and 15B schematically show the elevating mechanism for thewafer W, which is used in the electron beam processing apparatus. Asshown in FIG. 15A, each electron beam apparatus 1 in the aboverespective embodiments has a plurality of (e.g., three) elevating pins15 arranged on the bottom surface of the processing container 2. Asindicated by the arrow in FIG. 15A, the elevating pins 15 are verticallymoved when the wafer W is delivered to an outer wafer-conveyingmechanism and received therefrom. Each elevating pin 15 is composed of,for example, a pin portion 15A and a support portion 15B which isintegrally formed with the pin portion 15A. As shown in FIG. 15A, thesupport portion 15B passes through a bottom of the processing container2 in a vertically movable manner via an O-ring 16.

The pin portion 15A is formed by, e.g., depositing ceramics such asalumina on a surface of a metal such as stainless steel. The supportportion 15B is formed of a metal such as stainless steel or the like. Adeposition of the ceramics on the pin portion 15A insulates theelevating pin 15 from a ground electric potential. This prevents anelectric discharge when the electron beams are irradiated. In order toair-tightly seal the support portion 15B, the support portion 15B isprocessed from a metal material with high precision and the O-ring 16 isused therefor. The pin portion 15A may be naturally coated with anyother insulating material than ceramics. Alternatively, the pin portion15A itself may be formed of an insulating material such as ceramics.Since the elevating pin 15 has such a constitution, measures against anelectric discharge can be taken, while employing a vacuum sealingconstitution of the processing container 2. As a result, the EB cure canbe surely and favorably carried out. In addition, it is possible toreduce a cost for finishing a surface of the elevating pin 15 (abuttingsurface with the O-ring 16) with a desired processing precision. Theelevating pin 15 may be disposed on the stage 3 of the electron beamprocessing apparatus 1.

On the other hand, in a conventional electron beam processing apparatus100 shown in FIG. 15B, an elevating pin 115 is formed of a metal such asstainless steel. Thus, the elevating pin 115 is in a ground electricpotential. Therefore, an electric discharge may occur through theelevating pin 115 when the electron beams are irradiated. An electriccurrent may flow in a direction shown by the outline arrow in FIG. 15B,which may badly affect the EB cure. In FIG. 15B, the reference numbers102, 104, and 116 respectively indicate a processing container, anelectron beam tube, and an O-ring.

The present invention is not limited to the above embodiments. Variouschanges and modifications are included in the present invention withoutdeparting from the scope of the invention. For example, in the aboveembodiments, a temperature of the stage 3 is measured, and the measuredtemperature is used as a temperature of the wafer W. However, atemperature of the wafer W may be directly measured. In this case, anend point can be more accurately detected. Further, although the gridelectrode 5 is provided in the above embodiments, the present inventioncan be also applied to cases without grid electrode.

1-9. (canceled)
 10. A film-processing method comprising: a processingstep of irradiating electron beams onto a film on a surface of an objectto be processed to conduct a process to modify a quality of the film; anemission-intensity measuring step of measuring an intensity of theemission spectrum with respect to a certain wavelength of plasmacorresponding to a certain detached gas; and a detecting step ofdetecting an end point of the process based on the intensity of theemission spectrum obtained by the emission-intensity measuring step. 11.A film-processing method according to claim 10, wherein the certainwavelength is an emission wavelength of a hydrogen radical.
 12. Afilm-processing method according to claim 10, wherein the detecting stepdetects the end point of the process based on time integration of theintensity of the emission spectrum obtained by the emission-intensitymeasuring step.
 13. A film-processing method according to claim 10,further comprising: a calculating step of previously calculating, as areference value, an integrated intensity of the emission spectrum beforean end point of a reference process to a reference film on an object tobe processed, wherein the detecting process detects the end point of theprocess based on the reference value.
 14. A film-processing apparatuscomprising: a processing unit which irradiates electron beams onto afilm on a surface of an object to be processed to modify a quality ofthe film; an emission-intensity sensor which measures an intensity ofthe emission spectrum with respect to a certain wavelength of plasmacorresponding to a certain detached gas; and a detecting unit whichdetects an end point of the process based on the intensity of theemission spectrum measured by the emission-intensity sensor.
 15. Afilm-processing apparatus according to claim 14, wherein the certainwavelength is an emission wavelength of a hydrogen radical.
 16. Afilm-processing apparatus according to claim 14, further comprising: acalculating unit which calculates an integrated intensity of theemission spectrum by means of time integration of the intensity of theemission spectrum, wherein the detecting unit is adapted to detect theend point of the process based on the integrated intensity.
 17. Afilm-processing apparatus according to claim 16, further comprising: astoring unit which stores a reference value of an integrated intensityof the emission spectrum before an end point of a reference process to areference film on an object to be processed; wherein the detecting unitis adapted to detect the end point of the process based on the referencevalue.
 18. A film-processing apparatus according to claim 14, furthercomprising: a processing container; a stage disposed in the processingcontainer; and a plurality of electron beam tubes which irradiateelectron beams onto an object to be processed mounted on the stage. 19.A film-processing apparatus according to claim 14, wherein theemission-intensity sensor includes a collimator, an optical fiber and aspectrograph.